Many different power supplies have been developed over the years for various different applications. One power supply of interest here is an open loop, high voltage power supply that was initially designed for two NASA applications, Solar X-Ray Imager (SXI) and Solar Extreme Ultraviolet Research Telescope Spectrograph (SERTS). This power supply, which uses a pre-regulator, voltage doublers and a preload, generates a high voltage output with a fast rise/fall time and was used to electronically shutter a microchannel plate (MCP) intensified Charge Coupled Device (CCD) by controlling the accelerating voltage across the MCP. This approach has been used successfully in connection with the SXI telescope and in a number of different SERTS flights. However, this power supply is not of universal applicability and there are projects that require a fast rise/fall time that can benefit from use of a power supply based on an improved or different approach.